The club said it invoked a clause in the Brazilian's two-year contract to terminate his services.
Neiva, 46 was appointed on July 1 to replace Johnathan McKinstry, whose contract had expired and opted to join the Gambian national team
Gor Mahia have sacked head coach Leonardo Neiva after a poor start to the season that has seen the defending champions languishing in 12th place in this season's FKF Premier League table after six matches.
Assistant coaches Zedekiah Otieno and Michael Nam will oversee the club in the interim.
